// Copyright 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/base/tiling_data.h"

#include <algorithm>

#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/rect_f.h"
#include "ui/gfx/geometry/vector2d.h"

namespace cc {

namespace {
    // IndexRect which is at left top corner of the positive quadrant.
    const IndexRect kNonPositiveQuadrantIndexRect(-1, -1, -1, -1);
}

static int ComputeNumTiles(int max_texture_size,
    int total_size,
    int border_texels)
{
    if (max_texture_size - 2 * border_texels <= 0)
        return total_size > 0 && max_texture_size >= total_size ? 1 : 0;

    int num_tiles = std::max(1,
        1 + (total_size - 1 - 2 * border_texels) / (max_texture_size - 2 * border_texels));
    return total_size > 0 ? num_tiles : 0;
}

TilingData::TilingData()
    : border_texels_(0)
{
    RecomputeNumTiles();
}

TilingData::TilingData(const gfx::Size& max_texture_size,
    const gfx::Size& tiling_size,
    bool has_border_texels)
    : max_texture_size_(max_texture_size)
    , tiling_size_(tiling_size)
    , border_texels_(has_border_texels ? 1 : 0)
{
    RecomputeNumTiles();
}

TilingData::TilingData(const gfx::Size& max_texture_size,
    const gfx::Size& tiling_size,
    int border_texels)
    : max_texture_size_(max_texture_size)
    , tiling_size_(tiling_size)
    , border_texels_(border_texels)
{
    RecomputeNumTiles();
}

void TilingData::SetTilingSize(const gfx::Size& tiling_size)
{
    tiling_size_ = tiling_size;
    RecomputeNumTiles();
}

void TilingData::SetMaxTextureSize(const gfx::Size& max_texture_size)
{
    max_texture_size_ = max_texture_size;
    RecomputeNumTiles();
}

void TilingData::SetHasBorderTexels(bool has_border_texels)
{
    border_texels_ = has_border_texels ? 1 : 0;
    RecomputeNumTiles();
}

void TilingData::SetBorderTexels(int border_texels)
{
    border_texels_ = border_texels;
    RecomputeNumTiles();
}

int TilingData::TileXIndexFromSrcCoord(int src_position) const
{
    if (num_tiles_x_ <= 1)
        return 0;

    DCHECK_GT(max_texture_size_.width() - 2 * border_texels_, 0);
    int x = (src_position - border_texels_) / (max_texture_size_.width() - 2 * border_texels_);
    return std::min(std::max(x, 0), num_tiles_x_ - 1);
}

int TilingData::TileYIndexFromSrcCoord(int src_position) const
{
    if (num_tiles_y_ <= 1)
        return 0;

    DCHECK_GT(max_texture_size_.height() - 2 * border_texels_, 0);
    int y = (src_position - border_texels_) / (max_texture_size_.height() - 2 * border_texels_);
    return std::min(std::max(y, 0), num_tiles_y_ - 1);
}

int TilingData::FirstBorderTileXIndexFromSrcCoord(int src_position) const
{
    if (num_tiles_x_ <= 1)
        return 0;

    DCHECK_GT(max_texture_size_.width() - 2 * border_texels_, 0);
    int inner_tile_size = max_texture_size_.width() - 2 * border_texels_;
    int x = (src_position - 2 * border_texels_) / inner_tile_size;
    return std::min(std::max(x, 0), num_tiles_x_ - 1);
}

int TilingData::FirstBorderTileYIndexFromSrcCoord(int src_position) const
{
    if (num_tiles_y_ <= 1)
        return 0;

    DCHECK_GT(max_texture_size_.height() - 2 * border_texels_, 0);
    int inner_tile_size = max_texture_size_.height() - 2 * border_texels_;
    int y = (src_position - 2 * border_texels_) / inner_tile_size;
    return std::min(std::max(y, 0), num_tiles_y_ - 1);
}

int TilingData::LastBorderTileXIndexFromSrcCoord(int src_position) const
{
    if (num_tiles_x_ <= 1)
        return 0;

    DCHECK_GT(max_texture_size_.width() - 2 * border_texels_, 0);
    int inner_tile_size = max_texture_size_.width() - 2 * border_texels_;
    int x = src_position / inner_tile_size;
    return std::min(std::max(x, 0), num_tiles_x_ - 1);
}

int TilingData::LastBorderTileYIndexFromSrcCoord(int src_position) const
{
    if (num_tiles_y_ <= 1)
        return 0;

    DCHECK_GT(max_texture_size_.height() - 2 * border_texels_, 0);
    int inner_tile_size = max_texture_size_.height() - 2 * border_texels_;
    int y = src_position / inner_tile_size;
    return std::min(std::max(y, 0), num_tiles_y_ - 1);
}

IndexRect TilingData::TileAroundIndexRect(const gfx::Rect& center_rect) const
{
    int around_left = 0;
    // Determine around left, such that it is between -1 and num_tiles_x.
    if (center_rect.x() < 0 || center_rect.IsEmpty())
        around_left = -1;
    else if (center_rect.x() >= tiling_size().width())
        around_left = num_tiles_x();
    else
        around_left = TileXIndexFromSrcCoord(center_rect.x());

    // Determine around top, such that it is between -1 and num_tiles_y.
    int around_top = 0;
    if (center_rect.y() < 0 || center_rect.IsEmpty())
        around_top = -1;
    else if (center_rect.y() >= tiling_size().height())
        around_top = num_tiles_y();
    else
        around_top = TileYIndexFromSrcCoord(center_rect.y());

    // Determine around right, such that it is between -1 and num_tiles_x.
    int around_right = 0;
    int right_src_coord = center_rect.right() - 1;
    if (right_src_coord < 0 || center_rect.IsEmpty()) {
        around_right = -1;
    } else if (right_src_coord >= tiling_size().width()) {
        around_right = num_tiles_x();
    } else {
        around_right = TileXIndexFromSrcCoord(right_src_coord);
    }

    // Determine around bottom, such that it is between -1 and num_tiles_y.
    int around_bottom = 0;
    int bottom_src_coord = center_rect.bottom() - 1;
    if (bottom_src_coord < 0 || center_rect.IsEmpty()) {
        around_bottom = -1;
    } else if (bottom_src_coord >= tiling_size().height()) {
        around_bottom = num_tiles_y();
    } else {
        around_bottom = TileYIndexFromSrcCoord(bottom_src_coord);
    }

    return IndexRect(around_left, around_right, around_top, around_bottom);
}

gfx::Rect TilingData::ExpandRectIgnoringBordersToTileBounds(
    const gfx::Rect& rect) const
{
    if (rect.IsEmpty() || has_empty_bounds())
        return gfx::Rect();
    if (rect.x() > tiling_size_.width() || rect.y() > tiling_size_.height())
        return gfx::Rect();
    int index_x = TileXIndexFromSrcCoord(rect.x());
    int index_y = TileYIndexFromSrcCoord(rect.y());
    int index_right = TileXIndexFromSrcCoord(rect.right() - 1);
    int index_bottom = TileYIndexFromSrcCoord(rect.bottom() - 1);

    gfx::Rect rect_top_left(TileBounds(index_x, index_y));
    gfx::Rect rect_bottom_right(TileBounds(index_right, index_bottom));

    return gfx::UnionRects(rect_top_left, rect_bottom_right);
}

gfx::Rect TilingData::ExpandRectToTileBounds(const gfx::Rect& rect) const
{
    if (rect.IsEmpty() || has_empty_bounds())
        return gfx::Rect();
    if (rect.x() > tiling_size_.width() || rect.y() > tiling_size_.height())
        return gfx::Rect();
    int index_x = FirstBorderTileXIndexFromSrcCoord(rect.x());
    int index_y = FirstBorderTileYIndexFromSrcCoord(rect.y());
    int index_right = LastBorderTileXIndexFromSrcCoord(rect.right() - 1);
    int index_bottom = LastBorderTileYIndexFromSrcCoord(rect.bottom() - 1);

    gfx::Rect rect_top_left(TileBounds(index_x, index_y));
    gfx::Rect rect_bottom_right(TileBounds(index_right, index_bottom));

    return gfx::UnionRects(rect_top_left, rect_bottom_right);
}

gfx::Rect TilingData::TileBounds(int i, int j) const
{
    AssertTile(i, j);
    int max_texture_size_x = max_texture_size_.width() - 2 * border_texels_;
    int max_texture_size_y = max_texture_size_.height() - 2 * border_texels_;

    int lo_x = max_texture_size_x * i;
    if (i != 0)
        lo_x += border_texels_;

    int lo_y = max_texture_size_y * j;
    if (j != 0)
        lo_y += border_texels_;

    int hi_x = max_texture_size_x * (i + 1) + border_texels_;
    if (i + 1 == num_tiles_x_)
        hi_x += border_texels_;

    int hi_y = max_texture_size_y * (j + 1) + border_texels_;
    if (j + 1 == num_tiles_y_)
        hi_y += border_texels_;

    hi_x = std::min(hi_x, tiling_size_.width());
    hi_y = std::min(hi_y, tiling_size_.height());

    int x = lo_x;
    int y = lo_y;
    int width = hi_x - lo_x;
    int height = hi_y - lo_y;
    DCHECK_GE(x, 0);
    DCHECK_GE(y, 0);
    DCHECK_GE(width, 0);
    DCHECK_GE(height, 0);
    DCHECK_LE(x, tiling_size_.width());
    DCHECK_LE(y, tiling_size_.height());
    return gfx::Rect(x, y, width, height);
}

gfx::Rect TilingData::TileBoundsWithBorder(int i, int j) const
{
    AssertTile(i, j);
    int max_texture_size_x = max_texture_size_.width() - 2 * border_texels_;
    int max_texture_size_y = max_texture_size_.height() - 2 * border_texels_;

    int lo_x = max_texture_size_x * i;
    int lo_y = max_texture_size_y * j;

    int hi_x = lo_x + max_texture_size_x + 2 * border_texels_;
    int hi_y = lo_y + max_texture_size_y + 2 * border_texels_;

    hi_x = std::min(hi_x, tiling_size_.width());
    hi_y = std::min(hi_y, tiling_size_.height());

    int x = lo_x;
    int y = lo_y;
    int width = hi_x - lo_x;
    int height = hi_y - lo_y;
    DCHECK_GE(x, 0);
    DCHECK_GE(y, 0);
    DCHECK_GE(width, 0);
    DCHECK_GE(height, 0);
    DCHECK_LE(x, tiling_size_.width());
    DCHECK_LE(y, tiling_size_.height());
    return gfx::Rect(x, y, width, height);
}

int TilingData::TilePositionX(int x_index) const
{
    DCHECK_GE(x_index, 0);
    DCHECK_LT(x_index, num_tiles_x_);

    int pos = (max_texture_size_.width() - 2 * border_texels_) * x_index;
    if (x_index != 0)
        pos += border_texels_;

    return pos;
}

int TilingData::TilePositionY(int y_index) const
{
    DCHECK_GE(y_index, 0);
    DCHECK_LT(y_index, num_tiles_y_);

    int pos = (max_texture_size_.height() - 2 * border_texels_) * y_index;
    if (y_index != 0)
        pos += border_texels_;

    return pos;
}

int TilingData::TileSizeX(int x_index) const
{
    DCHECK_GE(x_index, 0);
    DCHECK_LT(x_index, num_tiles_x_);

    if (!x_index && num_tiles_x_ == 1)
        return tiling_size_.width();
    if (!x_index && num_tiles_x_ > 1)
        return max_texture_size_.width() - border_texels_;
    if (x_index < num_tiles_x_ - 1)
        return max_texture_size_.width() - 2 * border_texels_;
    if (x_index == num_tiles_x_ - 1)
        return tiling_size_.width() - TilePositionX(x_index);

    NOTREACHED();
    return 0;
}

int TilingData::TileSizeY(int y_index) const
{
    DCHECK_GE(y_index, 0);
    DCHECK_LT(y_index, num_tiles_y_);

    if (!y_index && num_tiles_y_ == 1)
        return tiling_size_.height();
    if (!y_index && num_tiles_y_ > 1)
        return max_texture_size_.height() - border_texels_;
    if (y_index < num_tiles_y_ - 1)
        return max_texture_size_.height() - 2 * border_texels_;
    if (y_index == num_tiles_y_ - 1)
        return tiling_size_.height() - TilePositionY(y_index);

    NOTREACHED();
    return 0;
}

gfx::RectF TilingData::TexelExtent(int i, int j) const
{
    gfx::RectF result(TileBoundsWithBorder(i, j));
    result.Inset(0.5f, 0.5f);
    return result;
}

gfx::Vector2d TilingData::TextureOffset(int x_index, int y_index) const
{
    int left = (!x_index || num_tiles_x_ == 1) ? 0 : border_texels_;
    int top = (!y_index || num_tiles_y_ == 1) ? 0 : border_texels_;

    return gfx::Vector2d(left, top);
}

void TilingData::RecomputeNumTiles()
{
    num_tiles_x_ = ComputeNumTiles(
        max_texture_size_.width(), tiling_size_.width(), border_texels_);
    num_tiles_y_ = ComputeNumTiles(
        max_texture_size_.height(), tiling_size_.height(), border_texels_);
}

TilingData::BaseIterator::BaseIterator()
    : index_x_(-1)
    , index_y_(-1)
{
}

TilingData::Iterator::Iterator()
    : index_rect_(kNonPositiveQuadrantIndexRect)
{
    done();
}

TilingData::Iterator::Iterator(const TilingData* tiling_data,
    const gfx::Rect& consider_rect,
    bool include_borders)
    : index_rect_(kNonPositiveQuadrantIndexRect)
{
    if (tiling_data->num_tiles_x() <= 0 || tiling_data->num_tiles_y() <= 0) {
        done();
        return;
    }

    gfx::Rect tiling_bounds_rect(tiling_data->tiling_size());
    gfx::Rect rect(consider_rect);
    rect.Intersect(tiling_bounds_rect);

    gfx::Rect top_left_tile;
    if (include_borders) {
        index_x_ = tiling_data->FirstBorderTileXIndexFromSrcCoord(rect.x());
        index_y_ = tiling_data->FirstBorderTileYIndexFromSrcCoord(rect.y());
        index_rect_ = IndexRect(
            index_x_,
            tiling_data->LastBorderTileXIndexFromSrcCoord(rect.right() - 1),
            index_y_,
            tiling_data->LastBorderTileYIndexFromSrcCoord(rect.bottom() - 1));
        DCHECK(index_rect_.is_valid());
        top_left_tile = tiling_data->TileBoundsWithBorder(index_x_, index_y_);
    } else {
        index_x_ = tiling_data->TileXIndexFromSrcCoord(rect.x());
        index_y_ = tiling_data->TileYIndexFromSrcCoord(rect.y());
        index_rect_ = IndexRect(
            index_x_, tiling_data->TileXIndexFromSrcCoord(rect.right() - 1),
            index_y_, tiling_data->TileYIndexFromSrcCoord(rect.bottom() - 1));
        DCHECK(index_rect_.is_valid());
        top_left_tile = tiling_data->TileBounds(index_x_, index_y_);
    }

    // Index functions always return valid indices, so explicitly check
    // for non-intersecting rects.
    if (!top_left_tile.Intersects(rect))
        done();
}

TilingData::Iterator& TilingData::Iterator::operator++()
{
    if (!*this)
        return *this;

    index_x_++;
    if (index_x_ > index_rect_.right()) {
        index_x_ = index_rect_.left();
        index_y_++;
        if (index_y_ > index_rect_.bottom())
            done();
    }

    return *this;
}

TilingData::BaseDifferenceIterator::BaseDifferenceIterator()
    : consider_index_rect_(kNonPositiveQuadrantIndexRect)
    , ignore_index_rect_(kNonPositiveQuadrantIndexRect)
{
    done();
}

TilingData::BaseDifferenceIterator::BaseDifferenceIterator(
    const TilingData* tiling_data,
    const gfx::Rect& consider_rect,
    const gfx::Rect& ignore_rect)
    : consider_index_rect_(kNonPositiveQuadrantIndexRect)
    , ignore_index_rect_(kNonPositiveQuadrantIndexRect)
{
    if (tiling_data->num_tiles_x() <= 0 || tiling_data->num_tiles_y() <= 0) {
        done();
        return;
    }

    gfx::Rect tiling_bounds_rect(tiling_data->tiling_size());
    gfx::Rect consider(consider_rect);
    consider.Intersect(tiling_bounds_rect);

    if (consider.IsEmpty()) {
        done();
        return;
    }

    consider_index_rect_ = IndexRect(tiling_data->TileXIndexFromSrcCoord(consider.x()),
        tiling_data->TileXIndexFromSrcCoord(consider.right() - 1),
        tiling_data->TileYIndexFromSrcCoord(consider.y()),
        tiling_data->TileYIndexFromSrcCoord(consider.bottom() - 1));
    DCHECK(consider_index_rect_.is_valid());

    gfx::Rect ignore(ignore_rect);
    ignore.Intersect(tiling_bounds_rect);

    if (!ignore.IsEmpty()) {
        ignore_index_rect_ = IndexRect(tiling_data->TileXIndexFromSrcCoord(ignore.x()),
            tiling_data->TileXIndexFromSrcCoord(ignore.right() - 1),
            tiling_data->TileYIndexFromSrcCoord(ignore.y()),
            tiling_data->TileYIndexFromSrcCoord(ignore.bottom() - 1));
        DCHECK(ignore_index_rect_.is_valid());

        // Clamp ignore indices to consider indices.
        ignore_index_rect_.ClampTo(consider_index_rect_);

        // If ignore rect is invalid, reset.
        if (!ignore_index_rect_.is_valid())
            ignore_index_rect_ = kNonPositiveQuadrantIndexRect;

        if (ignore_index_rect_ == consider_index_rect_) {
            consider_index_rect_ = kNonPositiveQuadrantIndexRect;
            done();
            return;
        }
    }
}

bool TilingData::BaseDifferenceIterator::HasConsiderRect() const
{
    // Consider indices are either all valid or all equal to -1.
    DCHECK(consider_index_rect_.is_in_positive_quadrant() || consider_index_rect_ == kNonPositiveQuadrantIndexRect);
    return consider_index_rect_.left() != -1;
}

TilingData::DifferenceIterator::DifferenceIterator()
{
}

TilingData::DifferenceIterator::DifferenceIterator(
    const TilingData* tiling_data,
    const gfx::Rect& consider_rect,
    const gfx::Rect& ignore_rect)
    : BaseDifferenceIterator(tiling_data, consider_rect, ignore_rect)
{
    if (!HasConsiderRect()) {
        done();
        return;
    }

    index_x_ = consider_index_rect_.left();
    index_y_ = consider_index_rect_.top();

    if (ignore_index_rect_.Contains(index_x_, index_y_))
        ++(*this);
}

TilingData::DifferenceIterator& TilingData::DifferenceIterator::operator++()
{
    if (!*this)
        return *this;

    index_x_++;
    if (ignore_index_rect_.Contains(index_x_, index_y_))
        index_x_ = ignore_index_rect_.right() + 1;

    if (index_x_ > consider_index_rect_.right()) {
        index_x_ = consider_index_rect_.left();
        index_y_++;

        if (ignore_index_rect_.Contains(index_x_, index_y_)) {
            index_x_ = ignore_index_rect_.right() + 1;
            // If the ignore rect spans the whole consider rect horizontally, then
            // ignore_right + 1 will be out of bounds.
            if (ignore_index_rect_.Contains(index_x_, index_y_) || index_x_ > consider_index_rect_.right()) {
                index_y_ = ignore_index_rect_.bottom() + 1;
                index_x_ = consider_index_rect_.left();
            }
        }

        if (index_y_ > consider_index_rect_.bottom())
            done();
    }

    return *this;
}

TilingData::SpiralDifferenceIterator::SpiralDifferenceIterator()
{
    done();
}

TilingData::SpiralDifferenceIterator::SpiralDifferenceIterator(
    const TilingData* tiling_data,
    const gfx::Rect& consider_rect,
    const gfx::Rect& ignore_rect,
    const gfx::Rect& center_rect)
    : BaseDifferenceIterator(tiling_data, consider_rect, ignore_rect)
{
    if (!HasConsiderRect()) {
        done();
        return;
    }

    IndexRect around_index_rect = tiling_data->TileAroundIndexRect(center_rect);
    DCHECK(around_index_rect.is_valid());

    spiral_iterator_ = SpiralIterator(around_index_rect, consider_index_rect_,
        ignore_index_rect_);

    if (!spiral_iterator_) {
        done();
        return;
    }

    index_x_ = spiral_iterator_.index_x();
    index_y_ = spiral_iterator_.index_y();
}

TilingData::SpiralDifferenceIterator& TilingData::SpiralDifferenceIterator::
operator++()
{
    ++spiral_iterator_;

    if (!spiral_iterator_) {
        done();
        return *this;
    }

    index_x_ = spiral_iterator_.index_x();
    index_y_ = spiral_iterator_.index_y();

    return *this;
}

TilingData::ReverseSpiralDifferenceIterator::ReverseSpiralDifferenceIterator()
{
    done();
}

TilingData::ReverseSpiralDifferenceIterator::ReverseSpiralDifferenceIterator(
    const TilingData* tiling_data,
    const gfx::Rect& consider_rect,
    const gfx::Rect& ignore_rect,
    const gfx::Rect& center_rect)
    : BaseDifferenceIterator(tiling_data, consider_rect, ignore_rect)
{
    if (!HasConsiderRect()) {
        done();
        return;
    }

    IndexRect around_index_rect = tiling_data->TileAroundIndexRect(center_rect);
    DCHECK(around_index_rect.is_valid());

    reverse_spiral_iterator_ = ReverseSpiralIterator(
        around_index_rect, consider_index_rect_, ignore_index_rect_);

    if (!reverse_spiral_iterator_) {
        done();
        return;
    }

    index_x_ = reverse_spiral_iterator_.index_x();
    index_y_ = reverse_spiral_iterator_.index_y();
}

TilingData::ReverseSpiralDifferenceIterator&
TilingData::ReverseSpiralDifferenceIterator::
operator++()
{
    ++reverse_spiral_iterator_;

    if (!reverse_spiral_iterator_) {
        done();
        return *this;
    }

    index_x_ = reverse_spiral_iterator_.index_x();
    index_y_ = reverse_spiral_iterator_.index_y();

    return *this;
}

} // namespace cc
